Field of the Invention
The present invention relates to a lens apparatus suitable for a video camera, an electronic still camera, a TV camera, or the like that has a function of close-up shooting, and to an image pickup apparatus including the lens apparatus.
Description of the Related Art
Macro lenses have been known as image pickup optical systems that are used mainly for close-up shooting. In general, in close-up shooting, a distance from an object to an image pickup optical system is short, and hence the image pickup optical system or a photographer casts its shadow over the object in some cases. Thus, illumination is often needed in close-up shooting. Hitherto, xenon flash tubes have been used as light sources for image pickup. However, light from a xenon flash tube is instant pulsed light, and hence there is a problem in that an illuminated object image cannot be visually checked through a finder or the like.
As a measure for the problem, in recent years, light emitting diodes having a wide wavelength band in a visible region have been put into practical use. In each of Japanese Patent Application Laid-Open No. 2006-337422 and Japanese Patent Application Laid-Open No. 2011-247978, there is disclosed an illumination device configured to illuminate an object side with a light emitting diode that is arranged on a holding frame configured to hold a lens closest to an object side of an image pickup optical system.
In the illumination device disclosed in Japanese Patent Application Laid-Open No. 2006-337422, a plurality of white light emitting diodes are arranged in a circular manner on the outer peripheral portion of the holding frame, which is configured to hold the lens closest to the object side. The illumination device disclosed in Japanese Patent Application Laid-Open No. 2011-247978 uses a light guide portion having a circular optical path in which light propagates. It is also disclosed that an amount of light radiated from the illumination device is changed by changing a position of a light source in an optical axis direction.
In the illumination device disclosed in Japanese Patent Application Laid-Open No. 2006-337422, each light source is arranged such that a light emitting surface of the light source faces an optical axis direction of the image pickup apparatus. Thus, a large number of light sources are needed in order to uniformly illuminate an object.
In the illumination device disclosed in Japanese Patent Application Laid-Open No. 2011-247978, an interval between two light sources is short, and hence it is difficult to uniformly illuminate an object.